\begin{tikzpicture}
    \tkzDefPoints{0/0/A, 1/0/C, 3/0/B}
    \tkzDrawSegments[xianduan={below=0pt}](A,C)
    \tkzDrawSegments[xianduan={below=0pt}](C,B)
    \tkzDrawLine[add=0.2 and 0.2](A,B)
    \tkzLabelPoints[above=.5em](A,B,C)
\end{tikzpicture}

